Ball-bearing center for lathes.



No. 725,697. PATENTED APR. 21, 190s. I. H. GILMAN.

BALL BEARING CENTER FOR LATI-IES.

APPLIoA'rIoN FILED MAY 26. 1902.

N0 MODEL.

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UNITED STATES PATENT OFFICE.

ISAAC H. GILMAN, OF WORCESTER, MASSACHUSETTS, ASSIGNOR OF ONE- THIRD TO WILLIAM H. GATES, OF 'WORCESTER, MASSACHUSETTS.

BALL-BEARING CENTER FOR LATHE'S.

Application 1611 my 26,1902. serial No. 103,910. (No man.;

Figure l represents a side elevation of a lathe-center embodying my improved ballbearing. Fig. 2 is a side elevation with the rotating sleeve shown in central sectional view; and Fig. 3 represents the same View as I5 that shown inFig. 2,ibut shows a modification in the construction.

Similar reference-letters refer to parts in the different views.

The object of my present invention is to reduce the friction in the dead-center of a lathe by interposing between the shank or spindle adapted to be held in the lathe-center and a rotating sleeve carrying the center a ball-bearing adapted to receive the end thrust and allow the center to rotate with the piece to be turned.

My improved device is specially adapted to be used in `wood-turning lathes, where the piece to be turned is made to revolve with great rapidity. Y

Referring to the accompanying drawings,

similar A denotes the tapered shank of a spindleV adapted to-iit the tail-'stock of 4a lathe'in Vthe* usual manner in lathe-centers of this class. The tapered shank A is provided with a head comprising the cylindrical section A', thecylindrical section A2 of larger diameter forming a shoulder A3, and the cylindrical section A4, preferably having a tapered` end or tip A5. Between the cylindrical sections A2 and A4 is a beveled surface B, forming a track for a series of friction-balls B, which are held in a ball-'chamber B2, formed within a sleeve C, which is free to rotate. The sleeve C is provided with an internal screw-thread C to receive a screw-threadedannular collar D, which is free to rotate upon the cylindrical section A and by its contact with the shoulder A3 prevents the removal of the sleeve C. The forward end of the sleeve is reduced in diameter and incloses the section A4. The

interior of the sleeve is provided with a tapered surface C2, adapted to fitl the tapered surface A5 on the spindle. The forward closed end of the sleeve is provided with a cupshaped depression E to engage the wood to be turned, said depression being similar to that now formed in the dead-centers of wood-turning lathes, and in addition to the cup-shaped depression E the sleeve is provided with a central spur or point F. The cylindrical section A2, which in Fig. 2'is represented as integral with the spindle, in Fig. 3 is formed in a separate screw-threaded nut G', having a beveled edge G' to form a track or ball-race,

Vsaidnut G being screwed'upon the screwder J for the retaining-nut D, which engages the internal screw-threads C on the sleeve C. The construction shown in Fig. 3 allows the ball-race or track G to be nicely adj usted to secure the proper bearing between the frictionballs B and the ball-bearing surfaces, and also between the beveled surfaces C2 and A5.

What I claim as my invention, and desire to secure by Letters Patent, is-' l.V A dead-center for lathes consisting of a spindlehavinga tapered' shank adapted to Vb e held in the tail-stock of a turning-lathe, a

ball-bearingsurface or track formed on said spindle, an inclosing sleeve adapted to engage the work to be turned and rotating on said spindle and friction-balls inclosed between said sleeve and said spindle, substantially as described.

2. In a dead-center for lathes, the combination of a spindle adapted to be held in the tail-stock of a lathe and provided-with a cylindrical section A', shoulder A3 and a cylindrical section'A4 with a ball-track B, a sleeve C inclosing the end or head of said spindle with a series of friction-balls interposed between said sleeve and said ball-tracks, substantially as described.

3. -In a dead-center for lathes, the combination with a spindle adapted so support on IOO its end a rotating sleeve, said spindle having a ball-track thereon, of a sleeve nelosing said ball-track, a series of balls interposed between said sleeve and spindle and a collar attached to said sleeve by which said sleeve is held upon said spindle, substantially as described.

4. In a dead-Center for lathes, the combination with a spindle and a sleeve arranged to rotate thereon and provided with means for engaging the work to be turned, of a screw threaded section on said spindle, a ball-bearing nut screwed upon said screw-threaded seetion and having a ball track or race, a cheeknut by'which said ball-bearing nut is held in 

